WebIDL.hs

-- | Stability: experimental
-- | This module defines some types from the [Web IDL](https://webidl.spec.whatwg.org/) specification
module Crypto.WebAuthn.WebIDL
  ( DOMString,
    USVString,
    UnsignedLongLong,
    UnsignedLong,
    Long,
    UnsignedShort,
    Octet,
    Boolean,
    Crypto.WebAuthn.WebIDL.Double,
    BufferSource (..),
    ArrayBuffer,
  )
where

import qualified Data.Aeson as Aeson
import qualified Data.ByteString as BS
import qualified Data.ByteString.Base64.URL as Base64
import Data.Int (Int32)
import Data.Text (Text)
import qualified Data.Text.Encoding as Text
import Data.Word (Word16, Word32, Word64, Word8)

-- | [(spec)](https://webidl.spec.whatwg.org/#idl-DOMString)
-- The `[DOMString](https://webidl.spec.whatwg.org/#idl-DOMString)` type
-- corresponds to the set of all possible sequences of
-- [code units](https://webidl.spec.whatwg.org/#dfn-code-unit). Such sequences
-- are commonly interpreted as UTF-16 encoded strings
-- [RFC2781](https://webidl.spec.whatwg.org/#biblio-rfc2781) although this is not required.
-- TODO: This implementation doesn't allow invalid UTF-16 codepoints, which
-- probably makes it not work regarding <https://www.w3.org/TR/webauthn-2/#sctn-strings>
-- Write a test case that doesn't work and find a better representation.
type DOMString = Text

-- | [(spec)](https://webidl.spec.whatwg.org/#idl-USVString)
-- The `[USVString](https://webidl.spec.whatwg.org/#idl-USVString)` type
-- corresponds to the set of all possible sequences of
-- [Unicode scalar values](http://www.unicode.org/glossary/#unicode_scalar_value),
-- which are all of the Unicode code points apart from the surrogate code points.
-- TODO: This implementation allows for surrogate code points. Figure out if
-- this can violate the spec in any way.
type USVString = Text

-- | [(spec)](https://webidl.spec.whatwg.org/#idl-unsigned-long)
type UnsignedLong = Word32

-- | [(spec)](https://webidl.spec.whatwg.org/#idl-unsigned-long)
type UnsignedLongLong = Word64

-- | [(spec)](https://webidl.spec.whatwg.org/#idl-long)
type Long = Int32

-- | [(spec)](https://webidl.spec.whatwg.org/#idl-unsigned-short)
type UnsignedShort = Word16

-- | [(spec)](https://webidl.spec.whatwg.org/#idl-octet)
type Octet = Word8

-- | [(spec)](https://webidl.spec.whatwg.org/#idl-boolean)
type Boolean = Bool

-- | [(spec)](https://webidl.spec.whatwg.org/#idl-double)
type Double = Prelude.Double

-- | [(spec)](https://webidl.spec.whatwg.org/#BufferSource)
newtype BufferSource = -- | base64url encoded buffersource as done by https://github.com/github/webauthn-json
  URLEncodedBase64 {unUrlEncodedBase64 :: BS.ByteString}
  deriving (Show, Eq)

instance Aeson.FromJSON BufferSource where
  parseJSON = Aeson.withText "base64url" $ \t ->
    either fail (pure . URLEncodedBase64) (Base64.decode $ Text.encodeUtf8 t)

instance Aeson.ToJSON BufferSource where
  toJSON (URLEncodedBase64 bs) = Aeson.String . Text.decodeUtf8 . Base64.encodeUnpadded $ bs

-- | [(spec)](https://webidl.spec.whatwg.org/#idl-ArrayBuffer)
type ArrayBuffer = BufferSource